Process of manufacturing hydroxy acid greases and product thereof



Patented Aug. 19, 1952 PROCESS OF MANUFACTURING HYDROXY .ACID GREASESAND PRODUCTTHEREOF Lorne W. SproulegSarnia, Warren 0. Pattenden, 'Courtri'ght,-- and Laurence F. King, 'Sarnia, ntar-i0, Canada, ass-ignors toflStandard Oil De- *velopment Company, a corporation ofDelaware No. Drawing. ,7 Application May 20, I950,

" I iserial No. 163,328

'6 Claims. (01. 252-39) The presentinvention relates wanimproved process "of' preparing lubricating greases and, particularly, grea'sescontain-ing soaps of'hydroxy acidsgsuch as l2-hydroxy stearic-acid. In-par ti'cular, it relates to a process"bywhich' stable calcium base greases of superior consistency may be prepared underconditions 'of'dehydrationa's contrasted to the conventional hydration. L

In'f'application "Serial N0;.' 81,206, filed "March I2, 1949, by the presentapphcants; thereisde scribed a process "for making stable'calcium base greases suitable, for high temperature useiby using mono: or 'dihydroxy saturated. fatty acids, instead of normal fatty acids, forjpreparing the soaps which I thicken mpficanmgisns m grease consistency. The advantages of "thehy'droxy acids in the case of calc ium.base,.,grease's are pointed out application. 'IBrifly', these greases are stable at temperatures which would evaporate .the Water 'realfired}as.a stabilizer .Lin

the .older type calcium -base, greases. .According to the present invention, superior greasespi lower soap content may be obtained by improvements'inpr'ocessina- Y The specific phenomena thy-which stab1e ;calcium base-greases'may thus'beprepared under conditions of relative dehydration arenot clear. butitappears that-when a hydroxmfatty acid is used, which has one or two hydroxyvgroups attached to the chain, thesehydroxy groups in some manner perform'the function for which According to the present inVention,--it--is in ne that the'standard-methodof ing limejsoap greases is not satisfactory'f ionpreparing the oil= ata suitable temperatureyfor example, about 325"F. -Next, the soap-oil concentrate iscooled 'Whenopgrease's'containing' calcium soaps of hydroxy acids? The-norm'al procedure is carried out in to -a temperature close to the boiling pOintof waterrfor example, about 225 F., while additional mineral oil and small quantitiesof water are addedand stirred into the mixture. Finally, additional lubricating oil is added to the soap.- water-o'il mixture until a grease is obtained having the' desired consistency. This-product is then cooled --to a suita'ble drawing. temperature, for example, about R, and is drawn i'nto: 138,-: ceptacles or-packages. During the first or sapcnificationwstage,the soap is in'a semi-fl-uid state. If it is allowed 'to cool to 175 F. or so'without addition of further oil or water it forms a dry, hard, brittle mass. When water is incorporatedas in the second step given above, the soap-oil mixture forms a soft plastic composition of grease-like structure, If the productof' the 'first step is merely diluted with oilan'd cooled, for example, to about 175,F. or so without the'additio'n of water, the soap and oil .will, separate into'f'two phases. ,Ihishetero geneous product is quite worthle' and its components cannotbel dispersedin each other .to term a real'jg'rea'se ievenby" drastic nieehani'calw'c'irl zin'g. ,Accordingto the present invention; although the greases containing hydroxy' acids "can {be made substantially -ar'ihyclrous, care mustv be taken in dehydratin them. If the soapstocii'or c'on'cent'rateis merely heated in a sn' iall amount of 'oilf'to'a temp'erature'of about 306 'F.'or so. and the'plQfi lg Ct then'allowed to' coolgthe' soap willfs'eparatefla'linosjt entirely from "the mama: ing'oil. This'separation occurs at a temperwture of about 275 F. and the s-oap'cannpt 'lbe subsequentlydispersedin the oil," e ven by" the additionfiof'water"followed'by a itationftf For purposes of the present invention, a preferred process by which a superior grease can be prepared is as follows: The hydroxy fatty acid, which may be 12-hydroxy stearic acid or other monoor dihydroxy fatty acids having from about 12 to 24 carbon atoms, is reacted with lime at a temperature of about 180 to 200 F., preferably about 190 F. The hydroxy acid and lime are preferably reacted in the presence of a relatively small amount of oil, for example, about /2 to 5 times as much oil, by weight, as hydroxy acid. The oil used is ordinarily mineral base lubricating oil of appropriate viscosity for the service for which the grease is prepared, i. e., between 60 and. 5,000, preferably about 100 to 1,000 S. U. S. at 100 F. The quantity of lubricating oil preferably should be from about equal to about four times the weight of the hydroxy acid. After the hydroxy acid and 7 little have thus been reacted in'the presence'of lubricating oil, the mass is slowly heated forslow 4 shows the increase in consistency which seem-- panied dehydration.

Percent Water in Grease (by distillation with gg ia Xylene) (77F.)

When dehydration was, finished, further oil (1400 lbs.) was worked into the soap stock until the worked penetration was 285/77 F. At this stage, the grease contained about 7% of 12-hydroxy stearic acid in the form of the calcium soap.

; .noted:

and controlled dehydration, with. continuous stirring, to a maximum temperature of about 250 to 300 F., preferably not above about 275F. The maximum temperature specifically preferred, especially for 12-hydroxy stearic acid, which is a preferred acid although others can be used, is

about 265 to 270 F. At such temperatures} the mixture is gradually dehydrated and after the .water is removed, further lubricating oil is I gradually added with continued stirring. As the temperature begins to drop, a grease of suitable structure readily forms. The remainder of the lubricating oil is then added while the grease is further cooled, with continued stirring, to a temperature of about180 to 210 51, preferably below200- At thelatter temperature, the grease maybe-drawn into packages or other containers. The fi'nishedproduct is not necessarily absolutely dry or anhydrous, but is substantially so. It may contain up to about 0.1% by weight of Water; .1 though a smaller water content, not greater than 0.05%, is preferred. Water is not an'. essential ingredient and ordinarily none is addedzi'ntentionally, as it must be in the prior art processes of preparing conventional calcium base greases. g

The. invention will be described further with reference to specific examples.

EXAMPLE'I 1) The process is essentially one of dehydra- :tion accompanied ,by mechanical shearing or milling. This is directly opposite to the manufacture of conventional lime soap grease which require hydration with 0.5 to 2% of water in order to obtain a stable dispersion of the soap.

(2) If the soap stock is not completely or substantially completely dehydrated, a grease of low yield is obtained. The water content should be down to 0.05% or less. Otherwise, an important advantage of the present invention, the reduction in soap requirements to attain a given consistency, is largely lost. In order to illustrate this, a portion of the soap stock (concentrate) of Example I, showing a worked penetration of 197 mm./ 10 with a water content of 0.2% was diluted with oil to form aggrease. With calculated hydroxy stearic acid content of 10.5%, a worked. penetration of 308 mm./10 was obtained. This is softfor such a soap content. Furthermore, on subsequent reheating such greases'tend to harden andform crustson the surface. The discovery of the" effect of very low water content led to "the. substantial"improvement of consistency (3 The, addition of water to a calcium' hy-" droxy stearate grease; after manufacture is com pleteddoes notaifec't the consistency of the objectionable. I

15 0 lbs. of 12-hydroxy .stearic acid (commercial grade) were charged to a 4000 lb. steam-jacketed kettle'and .570 lbs. of mineral 'oil,(V. /100 F.: 300 S.fU. S.; V. I.: 54) added; The mixture was stirred and heated to 190 F. to obtain solution of the fatty acid in the oil. r

22 lbs. of hydrated lime in the form of a slurry with about 80 lbs. of water'were added to the fatty acid-oil solution and the mixture stirred for /g hour. The contents were then allowed to stand for 10-18 hours, although it is not believed I ehydration was carried out, the maximu m temperature being about 250 F. Thisproces's r equired about 14 hours. The following table -(4)' on theother hand, if a'sample of soap stock, such as the concentrate of Example I, con taining 0.2%-water as above, is dehydrated in an oven at 250 F. without stirring, a product containing many hard'lumps of soap is obtained. This illustrates the necessity of agitation during the dehydration. i i

. XAM I Another grease was prepared by the same method asthe grease of Example I, except that anzoil. of higherviscosity was used. The ingredients are;indicated in Table I where comparae tive .tests .with and without milling are shown of bothgreases, Examples I. and II. Results indicated that milling of the greases resulted in considerable improvement in their characteristics. h wh elbe r n test. show considerable a age in the unmilled grease of Example-1.;{Ihe milled greaseshowed no leakage whatever. Milli g weslipuhr $0.1m roreihe v os t b e Apparent Viscosity at lscf. :i a.oi, nnrits or CALO U-MHYDROXY summits Gamers Grease .Examp el Examp e I Formula, percent by weight:

12-Hydroxy Stearic Acid 7. 0 6.40 .I I drated Lima... 1.0 0.95 L T 20138.59.VJlOO,"v F.; 300; V. 1. 540 9,1. 5 24. 60 LO'P'lOBBSC V;/100 F; 1350;V. I. 54%.- -L 68. O5 iPllel ylnjlpha Naphtliylamina; -.1., 0-5

jtbweoldkr stMineralgon.

' Inspections Mineral Oil- V./210-"-'F.-'S. U. S

Benetrationn Worked Penetration 77, l3

A. S. T. M. Dropping Point F Jee nzr-Psrcentml L ss.

100,113,. at 225 F.)

O. R. 0. Wheel Bearing Test Glu at. 220

rease Leakage(gms.).

1 These values repr s n difierenttests. on, the same sample.

Separated.

EXAMPLE'III -Another :calcium base grease vgcontaining 12- hydroxystearic acid .andzmineral lubricating. oil of about 300 S. U. S. viscosity at 100 F. was prepared in the manner described above in a conventional grease kettle. This product showed the following characteristics and inspections:

Composition percent by weight:

12 -hydroxy stearic acid (comm.

grade) 10.5 Hydrated lime 1.5 Mineral oil (V. I 54; V./l00 F.: 300) 88.0

Inspections Worked penetration 77 F. (mm/l0)--- 2'73 A. S. T. M. Dropping Point F 288 C. R. C. Wheel Bearing Test:

Grams of grease leakage 0 Rating Excellent Upon passage of the product of Example I through a laboratory colloid mill no change in consistency was observed.

EXAMPLE IV Another grease composition likewise containing calcium soap of 12-hydroxy stearic acid and an oil of similar viscosity index (about 55) but of higher viscosity, about 900 S. U. S. at 100 F.,

was prepared in the same manner. As finished in the grease kettle, this product showed a worked penetration, after 60 strokes in the standard ASTM grease worker equipped with inch holes, of 281 mm./10. This product contained about 9.5% by weight, based on the total composition, of the calcium soap. It was slightly grainy in structure. After one passage through the laboratory colloid mill, the grease was hardened some-' what and its raininess somewhat reduced. It showed a worked penetration of 235 mm./10. Thereafter, additional oil was stirred into the grease until the worked penetration increased to 286 mm./10. The soap content of the finished product was about 6.1% by'weight. The com parative characteristics of thegrease offExaniple IV, the. same grease after passage through" the colloid mill, and the milled grease which was out back with additional oil, are shown in the following table:

From'the data given in the above examples. the following conclusions are drawn concerning the preparation of hydroxy acid greases.

' (1) The grease must be prepared at a maximum temperature not more than about 275 F., preferably about 270F.

(2) With oils of higher viscosity, the product should be finished by milling to improve its texture. When thi is done, greases of excellent properties and extremely low soap content, in view of the consistency of the product, may be obtained.

In cooking the soap, dehydration should be carried out slowly. Rapid cooking seems to destroy stability.

The greases prepared above in Examples HI and IV were made in IOU-pound batches. Full scale plant batches were made of Examples I and II. The data based on Examples I and II are, therefore, somewhat more firm. Furthermore, the control of dehydration was better in Examples I and II.

The'usual additives and modifiers, such as oxidation inhibitors, corrosion inhibitors, extreme pressure agents, and the like, may be used in the greases of this invention, if desired, as will be obvious to those skilled in the art. Preferred, types of greases usually contain from about'5 to'j 12% of the hydroxy acid, preferably 12-hydroxy stearic acid, in the form of the calcium soap, but proportions may be as low as 2% or as high as 30%, based on the weight of the final composition. I

What is claimed is: I

1. The process of preparing a substantially anhydrous lubricating grease which comprises saponifying 2 to 30% by weight, based on the total final composition, of hydroxy acid selected from the group which consists of substantially saturated monoand dihydroxy fatty acids which range between about 12 and about 24 carbon atoms per molecule with lime in the presence of calcium soap of a substantially saturated hydroxy acid selected from the group which consists of mono and dihydroxy fatt'y affidshaving not less than 112 nor more than 24 carbon atoms per molecule, said grease being'cooked to a maximum temperature not above 275 F. duringsoap forma- ;..;tion.

4. The product accordingto mantis wherein the hydroxy acid is l21-hydrpxy stearicja'cidi about one-half to about five times the quantity v of mineral base lubricating oil based on the weight I I of the hydroxy acids and at a maximum cooking temperature below about 275 F., and thereafter adding additional lubricating oil as the Y oil-soap mixture is cooled, with continuous stirring, until a temperature of about 200 F. is-

reached.

2. The process according to claim 1,wherein" the grease is passed through a colloid mill after cooling'to improve its performance in anti-fric j tion bearings.

3. A lubricating grease composition consist-- ing essentially of mineral base lubricating oil having a viscosity between 60 and ,5,000 S. U. .S. atLIjOOfF F. and thickened" to grease consistency with'about 2 'to 30% 'by Weight, based'fon the total composition. of "substantially anhydrous 5. The process of preparing a substantially anhydrous lubricating grease which comprises saponifying about 2 to 30% by weight, based on the total composition, of 12-hydroxy stearic acid, with lime at=a maximum cooking temperature of 275 F., in the presence of to 5 times as much mineral lubricating oil as acid, cooking slowly to gradually dehydrate and forma soap concentrate, and then adding further mineral oil and stirring while cooling to about 190 F.

6.'Process according to claimfl5 wherein'the proportionsof acid are between 5 and 12% by weight.

LORNE W. SPROULE. WARREN C. PATTENDEN. LAURENCE F. KING.

REFERENCES CI' IED ,Thefollowing references are of'record inthe file of .this .patent:

UNITED STATES PATENTS I Number Name Date 2,380,960 Fraser Aug. 7, 1945 2,450,224 Bergmann et a1. Sept. 28, 1948 2,503,749 Langer et a1, Apr.'1l, 1950 

1. THE PROCESS OF PREPARING A SUBSTANTIALLY ANHYDROUS LUBRICATING GREASE WHICH COMPRISES SAPONIFYING 2 TO 30% BY A WEIGHT, BASED ON THE TOTAL FINAL COMPOSITION, THE HYDROXY ACID SELECTED FROM THE GROUP WHICH CONSISTS OF SUBSTANTIALLY SATURATED MONO- AND DIHYDROXY FATTY ACIDS WHICH RANGE BETWEEN ABOUT 12 AND ABOUT 24 CARBON ATOMS PER MOLECULE WITH LIME IN THE PRESENCE OF ABOUT ONE-HALF TO ABOUT FIVE TIMES THE QUANTITY OF MINERAL BASE LUBRICATING OIL BASED ON THE WEIGHT OF THE HYDROXY ACIDS AND AT A MAXIMUM COOKING TEMPERATURE BELOW ABOUT 275* F., AND THEREAFTER ADDING ADDITIONAL LUBRICATING OIL AS THE OIL-SOAP MIXTURE IS COOLED, WITH CONTINUOUS STIRRING UNTIL A TEMPERATURE OF ABOUT 200* F. IS REACHED. 